As a wearer of glasses, I totally get it. It's basically impossible for another person to put someone's glasses on them correctly. They won't get the arms behind the ears properly or get the bridge at the right spot on the nose. Sometimes they might even poke you in the eye in the attempt. In any case it always feels wrong and is irritating out of proportion to the actual physical discomfort involved. So doing it repeatedly... think of this as a kind of water-drop torture, but with glasses.

I used to wear glasses (had corrective eye surgery) and any time someone else put my glasses on for me (like at the optometrist) it always felt weird and out of place. Would immediately go to push them up higher on my nose.

That urge to push glasses up your nose though will last for a long time even after you don't wear glasses anymore.